Among components used in semiconductor manufacturing apparatuses, the components for apparatuses used in an etching process, a CVD film-forming process, and an ashing process for removing a resist, which are based mainly on plasma processing, are exposed to halogen-type corrosive gasses such as fluorine or chlorine that are highly reactive.
Therefore, in the components that are exposed to halogen plasma in processes such as mentioned above, ceramics such as aluminum oxide, aluminum nitride, yttrium oxide and YAG are used as constituent materials. In particular, among the ceramics, the aluminum nitride having a high thermal conductivity and good corrosion resistance is favorably used in consideration of performance/cost balance.
Examples of such conventional ceramic components for plasma apparatuses may include electrostatic chucks disclosed in Patent Document 1 in which a metal electrode is embedded inside the aluminum nitride, a volume resistivity of a dielectric layer provided between a wafer and the inside electrode is adjusted to be 108 to 1012 Ω·cm, whereby what is called a Johnsen-Rahbek force, which provides an enhanced wafer adsorption force at a low temperature, is generated so as to adsorb the wafer.
However, since aluminum nitride is a sintering-retardant material, sintering is performed with a sintering aid added to aluminum nitride raw material powder. The mechanism of the sintering is that: addition of the sintering aid generates low-melting-point reaction products at particle boundaries, which brings the particle boundaries into a liquid phase and mass transfer of aluminum nitride is performed via the liquid phase. Accordingly, many particle boundary layers exist among the particles of the sintered body, and when stresses are concentrated at particle boundaries, breakage of the sintered body starts and advances from the particle boundaries, resulting in dropout of particles.
Thus, in the case of a component for a plasma apparatus (electrostatic chuck), since adsorption of a wafer to the component and desorption of the wafer from the component are repeated, a stress is caused on an adsorption surface of the component composed of aluminum nitride for plasma apparatuses. Therefore, there may be posed a problem such that particles are generated due to particle dropout and the wafers are contaminated by the particles.
Therefore, Patent Document 1 proposes a component for a plasma apparatus (electrostatic chuck) using an aluminum nitride in which amount of sintering aid is controlled and breakage of particle boundaries is suppressed, the particle boundaries being likely to be sources of generation of particles.
Patent Document 1 also proposes a component for a plasma apparatus (electrostatic chuck) using an aluminum nitride in which the generation of particles is suppressed by addition of, e.g., titanium nitride.